Seal shoe for a hydrostatic non-contact seal device

ABSTRACT

A non-contact seal assembly is provided. This assembly includes a plurality of seal shoes, a seal base and a plurality of spring elements. The seal shoes are arranged about a centerline in an annular array. The seal shoes include a first seal shoe extending axially along the centerline between a first shoe end and a second shoe end. An aperture may extend partially axially into the first seal shoe from the first shoe end and laterally within the first seal shoe. The seal base circumscribes the annular array of the seal shoes. Each of the spring elements is radially between and connects a respective one of the seal shoes with the seal base.

This invention was made with government support under Contract No.FA8650-09-D-2923-AETD awarded by the United States Air Force. Thegovernment may have certain rights in the invention.

BACKGROUND OF THE INVENTION

1. Technical Field

This disclosure relates generally to rotational equipment and, moreparticularly, to a non-contact seal assembly for rotational equipment.

2. Background Information

Rotational equipment typically includes one or more seal assemblies forsealing gaps between rotors and stators. A typical seal assemblyincludes a contact seal with a seal element such as a knife edge sealthat engages a seal land. Such a contact seal, however, can generate asignificant quantity of heat which can reduce efficiency of therotational equipment as well as subject other components of therotational equipment to high temperatures and internal stresses. Toaccommodate the high temperatures and stresses, certain components ofthe rotational equipment may be constructed from specialty hightemperature materials, which can significantly increase themanufacturing and servicing costs as well as the mass of the rotationalequipment. While non-contact seals have been developed in an effort toreduce heat within rotational equipment, there is still room forimprovement to provide an improved non-contact seal.

SUMMARY OF THE DISCLOSURE

According to an aspect of the present disclosure, a non-contact sealassembly is provided. This assembly includes a plurality of seal shoes,a seal base and a plurality of spring elements. The seal shoes arearranged about a centerline in an annular array. The seal shoes includea first seal shoe extending axially along the centerline between a firstshoe end and a second shoe end. An aperture extends partially axiallyinto the first seal shoe from the first shoe end and laterally withinthe first seal shoe. The seal base circumscribes the annular array ofthe seal shoes. Each of the spring elements is radially between andconnects a respective one of the seal shoes with the seal base.

According to another aspect of the present disclosure, anothernon-contact seal assembly is provided. This assembly includes aplurality of seal shoes, a seal base and a plurality of spring elements.The seal shoes are arranged about a centerline in an annular array. Theseal shoes include a first seal shoe extending axially along thecenterline between a first shoe end and a second shoe end. An apertureextends partially axially into the first seal shoe from the first shoeend and laterally through the first seal shoe along an entire laterallength of the first seal shoe. The seal base circumscribes the annulararray of the seal shoes. Each of the spring elements is radially betweenand connects a respective one of the seal shoes with the seal base.

According to another aspect of the present disclosure, anothernon-contact seal assembly is provided. This assembly includes aplurality of seal shoes, a seal base and a plurality of spring elements.The seal shoes are arranged about a centerline in an annular array. Theseal shoes includes a first seal shoe extending axially along thecenterline between a first shoe end and a second shoe end. The firstseal shoe includes a major region and a minor region disposed within themajor region at the first shoe end. The minor region has a mass/volumeratio that is less than a mass/volume ratio of the major region. Theseal base circumscribes the annular array of the seal shoes. Each of thespring elements is radially between and connects a respective one of theseal shoes with the seal base.

According to still another aspect of the present disclosure, an assemblyis provided for rotational equipment with an axial centerline. Thisassembly includes a stator structure, a rotor structure and a sealassembly. The seal assembly is configured to substantially seal anannular gap between the stator structure and the rotor structure. Theseal assembly includes a hydrostatic non-contact seal device, whichincludes a plurality of seal shoes, a seal base and a plurality ofspring elements. The seal shoes are arranged about a centerline in anannular array. The seal shoes sealingly engage the rotor structure andinclude a first seal shoe extending axially along the centerline betweena first shoe end and a second shoe end. An aperture extends partiallyaxially into the first seal shoe from the first shoe end and laterallywithin the first seal shoe. The seal shoes circumscribe and sealinglyengage the rotor structure. The seal base circumscribes the annulararray of the seal shoes. The seal base is mounted with the statorstructure. Each of the spring elements is radially between and connectsa respective one of the seal shoes with the seal base.

The stator structure and the rotor structure may be configured for aturbine engine.

The aperture may extend partially radially into the first seal shoe froman outer radial surface of the first seal shoe.

The aperture may extend radially within the first seal shoe.

The aperture may be one of a plurality of apertures extending axiallyinto the first seal shoe from the first shoe end and circumferentiallywithin the first seal shoe.

The apertures may be formed by a lattice structure.

The aperture may be at least partially filled with a material having adensity which is less than material from which another portion of thefirst seal shoe is formed.

The first seal shoe may extend circumferentially, at the first shoe end,between a first shoe side and a second shoe side for a seal shoe length.The aperture may extend laterally within the first seal shoe for anaperture length which is between about fifty percent and about eightypercent of the seal shoe length. Alternatively, the aperture length maybe between about ten percent and about fifty percent of the seal shoelength. Still alternatively, the aperture length may be between aboutone percent and about ten percent of the seal shoe length.

The seal shoes may collectively form a substantially annular end surfaceat the second end.

A ring structure and a secondary seal device may be included. The ringstructure may be axially engaged with the seal base. The secondary sealdevice may be mounted with the ring structure and axially engaged withthe substantially annular end surface. The secondary seal device may beconfigured to substantially seal an annular gap between the ringstructure and the annular array of the seal shoes.

The minor region may be configured as a portion of the first seal shoeat the first shoe end with a plurality of apertures therein.

A first of the apertures may extend partially axially into the firstseal shoe from the first shoe end and laterally within the first sealshoe.

The minor region may be configured with a lattice structure.

The minor region may be configured with a cellular structure.

The major region may be configured from or include a first material. Theminor region may be configured from or include a second materialdifferent from the first material. Alternatively, the second materialmay be the same as the first material.

The foregoing features and the operation of the invention will becomemore apparent in light of the following description and the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top-half side sectional illustration of an assembly forrotational equipment.

FIG. 2 is a perspective general representation of a primary seal devicefor the assembly of FIG. 1.

FIG. 3 is a top-half side sectional illustration of a primary sealdevice.

FIG. 4 is a cross-sectional illustration of a portion of the primaryseal device of FIG. 2.

FIG. 5 is another top-half side sectional illustration of the primaryseal device of FIG. 2.

FIG. 6 is another cross-sectional illustration of a portion of theprimary seal device of FIG. 2.

FIG. 7 is a cross-sectional illustration of a portion of another primaryseal device.

FIG. 8 is a cross-sectional illustration of a portion of another primaryseal device.

FIG. 9 is a cross-sectional illustration of a portion of another primaryseal device.

FIG. 10 is a cross-sectional illustration of a portion of anotherprimary seal device.

FIG. 11 is a top-half side sectional illustration of another primaryseal device.

FIG. 12 is a cross-sectional illustration of a portion of the primaryseal device of FIG. 11.

FIG. 13 is a side cutaway illustration of a gas turbine engine.

FIG. 14 is a cross-sectional illustration of a portion of anotherprimary seal device.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 illustrates an assembly 20 for rotational equipment with an axialcenterline 22. An example of such rotational equipment is a gas turbineengine for an aircraft propulsion system, an exemplary embodiment ofwhich is described below in further detail. However, the assembly 20 ofthe present disclosure is not limited to such an aircraft or gas turbineengine application. The assembly 20, for example, may alternatively beconfigured with rotational equipment such as an industrial gas turbineengine, a wind turbine, a water turbine or any other apparatus in whicha seal is provided between a stator structure and a rotor structure.

The assembly 20 of FIG. 1 includes a stator structure 24, a rotorstructure 26 and a seal assembly 28. This seal assembly 28 is mountedwith the stator structure 24, and configured to substantially seal anannular gap 30 between the stator structure 24 and the rotor structure26 as described below in further detail.

The stator structure 24 includes a seal carrier 32. This seal carrier 32may be a discrete, unitary annular body. Alternatively, the seal carrier32 may be configured with another component/portion of the statorstructure 24. The seal carrier 32 has an inner radial seal carriersurface 34. This seal carrier surface 34 may be substantiallycylindrical, and extends circumferentially around and faces towards theaxial centerline 22. The seal carrier surface 34 at least partiallyforms a bore in the stator structure 24. This bore is sized to receivethe seal assembly 28, which may be fixedly attached to the seal carrier32 by, for example, a press fit connection between the seal assembly 28and the seal carrier surface 34.

The rotor structure 26 includes a seal land 36. This seal land 36 may bea discrete, unitary annular body. Alternatively, the seal land 36 may beconfigured with another component/portion of the rotor structure 26. Theseal land 36 has an outer radial seal land surface 38. This seal landsurface 38 may be substantially cylindrical, and extendscircumferentially around and faces away from the axial centerline 22.The seal land surface 38 is disposed to face towards and is axiallyaligned with the seal carrier surface 34. While FIG. 1 illustrates thesurfaces 34 and 38 with approximately equal axial lengths along theaxial centerline 22, the seal land surface 38 may alternatively belonger or shorter than the seal carrier surface 34 in other embodiments.

The seal assembly 28 includes a primary seal device 40 and one or moresecondary seal devices 42; e.g., 1, 2, 3 or more secondary seal devices42. The seal assembly 28 also includes one or more additional componentsfor positioning, supporting and/or mounting one or more of the sealdevices 40 and 42 with the stator structure 24. The seal assembly 28 ofFIG. 1, for example, includes a first ring structure 44 configured forpositioning, supporting and/or mounting the secondary seal devices 42relative to the primary seal device 40. This first ring structure 44 mayalso be configured for axially positioning and/or supporting a secondend surface 46 of the primary seal device 40 relative to the statorstructure 24. The seal assembly 28 of FIG. 1 also includes a second ringstructure 48 (e.g., a scalloped support ring) configured for axiallypositioning and/or supporting a first end surface 50 of the primary sealdevice 40 relative to the stator structure 24. However, the second ringstructure 48 may be omitted where, for example, the first end surface 50of the primary seal device 40 may be abutted against anothercomponent/portion of the stator structure 24 (e.g., an annular orcastellated shoulder) or otherwise axially positioned/secure with thestator structure 24.

Referring to FIG. 2, the primary seal device 40 is configured as anannular non-contact seal device and, more particularly, a hydrostaticnon-contact seal device. An example of such a hydrostatic non-contactseal device is a “HALO™” seal; however, the primary seal device 40 ofthe present disclosure is not limited to the foregoing exemplaryhydrostatic non-contact seal device.

Referring to FIGS. 3 and 4, the primary seal device 40 includes a sealbase 52, a plurality of seal shoes 54 and a plurality of spring elements56. The seal base 52 is configured as an annular full hoop body, whichextends circumferentially around the axial centerline 22. The seal base52 is configured to circumscribe the seal shoes 54 as well as the springelements 56. The seal base 52 extends axially along the axial centerline22 between and forms the second end surface 46 and the first end surface50. The seal base 52 extends radially between an inner radial base side58 and an outer radial base side 60, which radially engages (e.g., ispress fit against) the stator structure 24 and, more particularly, theseal carrier surface 34 (see FIG. 1).

Referring to FIG. 2, the seal shoes 54 are configured as arcuate bodiesarranged circumferentially about the axial centerline 22 in an annulararray. This annular array of the seal shoes 54 extends circumferentiallyaround the axial centerline 22, thereby forming an inner bore at aninner radial side 62 of the primary seal device 40. As best seen in FIG.1, the inner bore is sized to receive the seal land 36, where the rotorstructure 26 projects axially through (or into) the inner bore formed bythe seal shoes 54.

Referring to FIG. 4, each of the seal shoes 54 extends radially from theinner radial side 62 of the primary seal device 40 to an outer radialsurface 64 of that seal shoe 54. Each of the seal shoes 54 extendscircumferentially around the axial centerline 22 between opposing firstand second circumferential sides 66 and 68 of that seal shoe 54.

Referring to FIG. 3, each of the seal shoes 54 extends axially along theaxial centerline 22 between a first shoe end 70 and a second shoe end72. The first shoe end 70 may be axially offset from and project axiallyaway from the first end surface 50. The second shoe end 72 may beaxially offset from and project axially away from the second end surface46. The seal shoes 54 of the present disclosure, however, are notlimited to such exemplary relationships.

Referring to FIG. 3, each of the seal shoes 54 includes an arcuate endsurface 74 generally at (e.g., on, adjacent or proximate) the secondshoe end 72. In the array (see FIG. 2), these arcuate end surfaces 74collectively form a generally annular (but circumferentially segmented)end surface 76 configured for sealingly engaging with the secondary sealdevices 42; see FIG. 1. The seal shoes 54 of the present disclosure,however, are not limited to the foregoing exemplary configuration.

Referring to FIGS. 3 and 4, each of the seal shoes 54 includes one ormore arcuate protrusions 78, which collectively form one or more (e.g.,a plurality of axially spaced) generally annular (e.g.,circumferentially segmented) ribs 80 at the inner radial side 62. Distalinner radial ends 82 of one or more of these ribs 80 are configured tobe arranged in close proximity with (but not touch) and therebysealingly engage the seal land surface 38 in a non-contact manner (seeFIG. 1), where the rotor structure 26 project axially through (or into)the inner bore formed by the seal shoes 54. The ribs 80 therefore areconfigured, generally speaking, as non-contact knife edge seal elements.

Referring to FIG. 2, the spring elements 56 are arrangedcircumferentially about the axial centerline 22 in an annular array.Referring again to FIGS. 3 and 4, the spring elements 56 are alsoarranged radially between the seal shoes 54 and the seal base 52. Eachof the spring elements 56 is configured to connect a respective one ofthe seal shoes 54 with the seal base 52. The spring element 56 shown inFIG. 4, for example, includes one or more mounts 82 and 84 (e.g.,generally radial fingers/projections) and one or more springs 86 (e.g.,cantilever-leaf springs). The first mount 82 is connected to arespective one of the seal shoes 54 at (e.g., on, adjacent or proximate)the first circumferential side 66, where the opposing secondcircumferential side 68 of that seal shoe 54 is free floating. Thesecond mount 84 is connected to the seal base 52, and is generallycircumferentially aligned with or near the second circumferential side68. The springs 86 are radially stacked and spaced apart with oneanother. Each of these springs 86 extends laterally (e.g., tangentiallyor circumferentially) from the first mount 82 to the second mount 84.These spring elements 56 may thereby laterally overlap a majorcircumferential portion (e.g., ˜65-95%) of the seal shoe 54. The springelements 56 of the present disclosure, however, are not limited to theforegoing exemplary configuration or values.

During operation of the primary seal device 40, rotation of the rotorstructure 26 may develop aerodynamic forces and apply a fluid pressureto the seal shoes 54 causing the each seal shoe 54 to respectively moveradially relative to the seal land surface 38. The fluid velocity mayincrease as a gap between the seal shoe 54 and seal land surface 38increases, thus reducing pressure in the gap and drawing the seal shoe54 radially inwardly toward the seal land surface 38. As the gap closes,the velocity may decrease and the pressure may increase within the gap,thus, forcing the seal shoe 54 radially outwardly from the seal landsurface 38. The respective spring element 56 may deflect and move withthe seal shoe 54 to create a primary seal of the gap between the sealland surface 38 and ribs 80 within predetermined design tolerances.

As described above, the radial in and out movement of the seal shoes 54is influenced by the rotational velocity of the rotor structure 26.Where the rotational velocity (w) of the rotor structure 26 has afrequency (f=w÷2π) that is substantially equal to a natural frequency ofthe seal shoes 54, the seal shoes 54 may be subject to naturalvibrations. Such natural vibrations may result in one or more of thefollowing:

-   -   cause one or more of the seal shoes 54 and, more particularly,        one or more of the ribs 80 to radially contact the seal land        surface 38 thereby wearing to one or more of those components 36        and 54;    -   induce relatively high stresses within one or more of the seal        shoes 54, which may result in high cycle fatigue failure of one        or more of those seal shoes 54; and    -   increase leakage between one or more of the seal shoes 54 and        the seal land surface 38 as a result of an uneven gap between        those components 36 and 54.

The natural frequency of a seal shoe 54 is influenced by the mass ofthat seal shoe 54 and the stiffness of the spring elements 56 thatattach seal shoe 54 to the seal base 52. Increasing the stiffness of thespring elements 56, for example, may increase the natural frequency ofthat seal shoe 54. In another example, decreasing the mass of the sealshoe 54 may increase the natural frequency of that seal shoe 54.

In recognition of the foregoing, one or more or each of the seal shoes54 of FIGS. 5 and 6 includes at least a major region 88 and at least oneminor region 90. In the exemplary embodiment of FIGS. 5 and 6, the minorregion 90 is generally designated by areas encircled by dashed lines.The major region 88 of FIGS. 5 and 6 generally includes the remainingportion of the seal shoe 54 outside of the dashed lines. The term “majorregion” may describe a region of a seal shoe 54 that accounts for amajority (e.g., more than fifty percent) of a volume and/or a mass ofthat seal shoe 54, where the major region 88 has a first mass/volumeratio (e.g., density). The term “minor region” may describe a region ofa seal shoe 54 that accounts for a minority (e.g., less than fiftypercent) of the volume and/or the mass of the seal shoe 54, where theminor region 90 has a second mass/volume ratio that is less than thefirst mass/volume ratio.

The minor region 90 is configured with the major region 88 to tune thenatural frequency of the respective seal shoe 54. In particular, theminor region 90 is configured with the major region 88 to increase thenatural frequency of the respective seal shoe 54 to a value that isabove the frequency (f) of the rotor structure 26 at, for example,normal speed operation or high (e.g., maximum) speed operation. Here, incomparison to a seal shoe 700 as shown in FIG. 7 without major and minorregions 88 and 90, the natural frequency of the seal shoe 54 of FIGS. 5and 6 is increased by reducing the mass of the seal shoe 54 while, forexample, substantially maintaining the stiffness of the spring elements56. In this manner, the respective seal shoe 54 may be operable tosignificantly reduce or eliminate natural vibrations thereof duringoperation of the rotational equipment. Of course, in other embodiments,the minor region 90 may be configured with the major region 88 toincrease the natural frequency of the respective seal shoe 54 to a valuethat is between about 50% to about 90% (or another percentage) of thefrequency (f) of the rotor structure 26 at the normal speed operation orhigh (e.g., maximum) speed operation.

The minor region 90 of FIGS. 5 and 6 includes a portion of the seal shoe54 with at least one aperture 92; e.g., a notch, an indentation, adrill-hole, etc. This aperture 92 extends partially into (e.g., notthrough) the seal shoe 54 from the first shoe end 70. More particularly,the aperture 92 extends partially into the seal shoe 54 from a surface93 at (e.g., on, adjacent or proximate) the first shoe end 70. Theaperture 92 also extends laterally (e.g., circumferentially ortangentially) within (e.g., not into or through) the seal shoe 54. Theaperture 92 of FIGS. 5 and 6 also extends radially inward (e.g., notthrough) into the seal shoe 54 from the outer radial surface 64 of thatseal shoe 54. However, in other embodiments as shown in FIG. 8, theaperture 92 may extend radially within (e.g., not into or through) theseal shoe 54.

Referring again to FIGS. 5 and 6, the aperture 92 may be centrallylocated laterally between the first circumferential side 66 and thesecond circumferential side 68. In other embodiments, however, theaperture 92 may be located more towards or at one of the circumferentialsides 66, 68. That said, the aperture 92 generally should not becircumferentially aligned or directly adjacent with the first mount 82to reduce or prevent high stress concentrations in the seal shoeproximate the first mount 82.

The aperture 92 of FIG. 6 has an aperture length defined laterallybetween opposing surfaces 94 which form distal lateral ends of thataperture 92. This aperture length may be between about fifty percent andabout eighty percent of a length of the seal shoe 54. This seal shoelength is defined circumferentially between the first circumferentialside 66 and the second circumferential side 68. However, in otherembodiments as shown in FIG. 9, the aperture length may be between aboutten percent and about fifty percent of the seal shoe length. In stillother embodiments as shown in FIGS. 10 to 12, the aperture length may bebetween about one percent and about ten percent of the seal shoe length.The present disclosure, however, is not limited to the foregoingexemplary embodiments or values. For example, in some embodiments, theaperture length may be equal to the length of the seal shoe 54; e.g.,see FIG. 14.

Referring again to FIG. 1, while the primary seal device 40 is operableto generally seal the annular gap 30 between the stator structure 24 andthe rotor structure 26 as described above, fluid (e.g., gas) may stillflow axially through passages 96 defined by radial gaps between thecomponents 52, 54 and 56. The secondary seal devices 42 therefore areprovided to seal off these passages 96 and, thereby, further and morecompletely seal the annular gap 30.

Each of the secondary seal devices 42 may be configured as a ring sealelement such as, but not limited to, a split ring. Alternatively, one ormore of the secondary seal devices 42 may be configured as a full hoopbody ring, an annular brush seal or any other suitable ring-type seal.

The secondary seal devices 42 of FIG. 1 are arranged together in anaxial stack. In this stack, each of the secondary seal devices 42axially engages (e.g., contacts) another adjacent one of the secondaryseal devices 42. The stack of the secondary seal devices 42 is arrangedwith the first ring structure 44, which positions and mounts thesecondary seal devices 42 with the stator structure 24 adjacent theprimary seal device 40. In this arrangement, the stack of the secondaryseal devices 42 is operable to axially engage and form a seal betweenthe end surface 76 of the array of the seal shoes 54 and an annularsurface 98 of the first ring structure 44. These surfaces 76 and 98 areaxially aligned with one another, which enables the stack of thesecondary seal devices 42 to slide radially against, but maintainsealingly engagement with, the end surface 76 as the seal shoes 54 moveradially relative to the seal land surface 38 as described above.

The first ring structure 44 may include a secondary seal device supportring 100 and a retention ring 102. The support ring 100 is configuredwith an annular full hoop body, which extends circumferentially aroundthe axially centerline 22. The support ring 100 includes the annularsurface 98, and is disposed axially adjacent and engaged with the sealbase 52.

The retention ring 102 is configured with an annular full hoop body,which extends circumferentially around the axially centerline 22. Theretention ring 102 is disposed axially adjacent and engaged with thesupport ring 100, thereby capturing the stack of the secondary sealdevices 42 within an annular channel formed between the rings 100 and102. The stack of the secondary seal devices 42, of course, may also oralternatively be attached to one of the rings 100 and 102 by, forexample, a press fit connection and/or otherwise.

In some embodiments, one or more of the apertures 92 may be configuredas open apertures. The term “open aperture” may describe an aperturewhich is not filled with solid material, but occupied by a fluid such asair.

In some embodiments, one or more of the apertures 92 may be at leastpartially or completely filled with another material. This othermaterial may have a density that is less than a density of the materialfrom which another portion (e.g., the remaining portion) of the sealshoe 54 body is formed. For example, the filler material may be acellular material such a metal foam, whereas the remainder of the sealshoe 54 may be formed from a billet of material such as metal. Thecomposition of such filler material may be the same or different thanthe billet of material. The seal shoe 54 of the present disclosure,however, is not limited to the foregoing exemplary materials.

In some embodiments, referring to FIGS. 11 and 12, some or all of theapertures 92 in the minor region 90 may be formed by cellular structure104; e.g., a lattice structure (see FIGS. 11 and 12), an open or closedcell foam structure, etc. Such a cellular structure 104, of course, mayhave various configurations other than that illustrated in FIGS. 11 and12. The lattice structure 104 may be formed using additive manufacturing(e.g., 3D printing) and/or various other manufacturing techniques.

The present disclosure is not limited to the exemplary primary sealdevice type or configuration described above. Various other non-contactseals are known in the art and may be reconfigured in light of thedisclosure above to be included with the assembly 20 of the presentdisclosure. Other examples of non-contact seals are disclosed in U.S.Pat. Nos. 8,172,232; 8,002,285; 7,896,352; 7,410,173; 7,182,345; and6,428,009, each of which is hereby incorporated herein by reference inits entirety.

As described above, the assembly 20 of the present disclosure may beconfigured with various different types and configurations of rotationalequipment. FIG. 13 illustrates one such type and configuration of therotational equipment—a geared turbofan gas turbine engine 106. Such aturbine engine 106 includes various stator structures (e.g., bearingsupports, hubs, cases, etc.) as well as various rotor structures (e.g.,rotor disks, shafts, etc.) as described below, where the statorstructure 24 and the rotor structure 26 can respectively be configuredas anyone of the foregoing structures in the turbine engine 106 of FIG.13, or other structures not mentioned herein.

Referring still to FIG. 13, the turbine engine 106 extends along anaxial centerline 108 (e.g., the centerline 22) between an upstreamairflow inlet 110 and a downstream airflow exhaust 112. The turbineengine 106 includes a fan section 114, a compressor section 115, acombustor section 116 and a turbine section 117. The compressor section115 includes a low pressure compressor (LPC) section 115A and a highpressure compressor (HPC) section 115B. The turbine section 117 includesa high pressure turbine (HPT) section 117A and a low pressure turbine(LPT) section 117B.

The engine sections 114-117 are arranged sequentially along thecenterline 108 within an engine housing 118, a portion or component ofwhich may include or be connected to the stator structure 24. Thishousing 118 includes an inner case 120 (e.g., a core case) and an outercase 122 (e.g., a fan case). The inner case 120 may house one or more ofthe engine sections; e.g., an engine core. The outer case 122 may houseat least the fan section 114.

Each of the engine sections 114, 115A, 115B, 117A and 117B includes arespective rotor 124-128. Each of these rotors 124-128 includes aplurality of rotor blades arranged circumferentially around andconnected to one or more respective rotor disks. The rotor blades, forexample, may be faulted integral with or mechanically fastened, welded,brazed, adhered and/or otherwise attached to the respective rotordisk(s).

The fan rotor 124 is connected to a gear train 130, for example, througha fan shaft 132. The gear train 130 and the LPC rotor 125 are connectedto and driven by the LPT rotor 128 through a low speed shaft 133. TheHPC rotor 126 is connected to and driven by the HPT rotor 127 through ahigh speed shaft 134. The shafts 132-134 are rotatably supported by aplurality of bearings 136; e.g., rolling element and/or thrust bearings.Each of these bearings 136 is connected to the engine housing 118 by atleast one stationary structure such as, for example, an annular supportstrut.

During operation, air enters the turbine engine 106 through the airflowinlet 110. This air is directed through the fan section 114 and into acore gas path 138 and a bypass gas path 140. The core gas path 138 flowssequentially through the engine sections 115-117. The bypass gas path140 flows away from the fan section 114 through a bypass duct, whichcircumscribes and bypasses the engine core. The air within the core gaspath 138 may be referred to as “core air”. The air within the bypass gaspath 140 may be referred to as “bypass air”.

The core air is compressed by the compressor rotors 125 and 126 anddirected into a combustion chamber 142 of a combustor in the combustorsection 116. Fuel is injected into the combustion chamber 142 and mixedwith the compressed core air to provide a fuel-air mixture. This fuelair mixture is ignited and combustion products thereof flow through andsequentially cause the turbine rotors 127 and 128 to rotate. Therotation of the turbine rotors 127 and 128 respectively drive rotationof the compressor rotors 126 and 125 and, thus, compression of the airreceived from a core airflow inlet. The rotation of the turbine rotor128 also drives rotation of the fan rotor 124, which propels bypass airthrough and out of the bypass gas path 140. The propulsion of the bypassair may account for a majority of thrust generated by the turbine engine106, e.g., more than seventy-five percent (75%) of engine thrust. Theturbine engine 106 of the present disclosure, however, is not limited tothe foregoing exemplary thrust ratio.

The assembly 20 may be included in various aircraft and industrialturbine engines other than the one described above as well as in othertypes of rotational equipment; e.g., wind turbines, water turbines,rotary engines, etc. The assembly 20, for example, may be included in ageared turbine engine where a gear train connects one or more shafts toone or more rotors in a fan section, a compressor section and/or anyother engine section. Alternatively, the assembly 20 may be included ina turbine engine configured without a gear train. The assembly 20 may beincluded in a geared or non-geared turbine engine configured with asingle spool, with two spools (e.g., see FIG. 13), or with more than twospools. The turbine engine may be configured as a turbofan engine, aturbojet engine, a propfan engine, a pusher fan engine or any other typeof turbine engine. The present invention therefore is not limited to anyparticular types or configurations of turbine engines or rotationalequipment.

While various embodiments of the present invention have been disclosed,it will be apparent to those of ordinary skill in the art that many moreembodiments and implementations are possible within the scope of theinvention. For example, the present invention as described hereinincludes several aspects and embodiments that include particularfeatures. Although these features may be described individually, it iswithin the scope of the present invention that some or all of thesefeatures may be combined with any one of the aspects and remain withinthe scope of the invention. Accordingly, the present invention is not tobe restricted except in light of the attached claims and theirequivalents.

What is claimed is:
 1. A non-contact seal assembly, comprising: aplurality of seal shoes arranged about a centerline in an annular array,the seal shoes including a first seal shoe extending axially along thecenterline between a first shoe end and a second shoe end, wherein anaperture extends partially axially into the first seal shoe from thefirst shoe end and laterally within the first seal shoe; a seal basecircumscribing the annular array of the seal shoes; and a plurality ofspring elements, each of the spring elements radially between andconnecting a respective one of the seal shoes with the seal base.
 2. Theassembly of claim 1, wherein the aperture extends partially radiallyinto the first seal shoe from an outer radial surface of the first sealshoe.
 3. The assembly of claim 1, wherein the aperture extends radiallywithin the first seal shoe.
 4. The assembly of claim 1, wherein theaperture is one of a plurality of apertures extending axially into thefirst seal shoe from the first shoe end and circumferentially within thefirst seal shoe.
 5. The assembly of claim 4, wherein the apertures areformed by a lattice structure.
 6. The assembly of claim 1, wherein theaperture is an open aperture.
 7. The assembly of claim 1, wherein theaperture is at least partially filled with a material having a densitywhich is less than material from which another portion of the first sealshoe is formed.
 8. The assembly of claim 1, wherein the first seal shoeextends circumferentially, at the first shoe end, between a first shoeside and a second shoe side for a seal shoe length; and the apertureextends laterally within the first seal shoe for an aperture lengthwhich is between about fifty percent and about eighty percent of theseal shoe length.
 9. The assembly of claim 1, wherein the first sealshoe extends circumferentially, at the first shoe end, between a firstshoe side and a second shoe side for a seal shoe length; and theaperture extends laterally within the first seal shoe for an aperturelength which is between about ten percent and about fifty percent of theseal shoe length.
 10. The assembly of claim 1, wherein the first sealshoe extends circumferentially, at the first shoe end, between a firstshoe side and a second shoe side for a seal shoe length; and theaperture extends laterally within the first seal shoe for an aperturelength which is between about one percent and about ten percent of theseal shoe length.
 11. The assembly of claim 1, wherein the seal shoescollectively form a substantially annular end surface at the second end.12. The assembly of claim 11, further comprising: a ring structureaxially engaged with the seal base; and a secondary seal device mountedwith the ring structure and axially engaged with the substantiallyannular end surface; wherein the secondary seal device is configured tosubstantially seal an annular gap between the ring structure and theannular array of the seal shoes.
 13. A non-contact seal assembly,comprising: a plurality of seal shoes arranged about a centerline in anannular array, the seal shoes includes a first seal shoe extendingaxially along the centerline between a first shoe end and a second shoeend, the first seal shoe comprising a major region and a minor regiondisposed within the major region at the first shoe end, wherein theminor region has a mass/volume ratio that is less than a mass/volumeratio of the major region; a seal base circumscribing the annular arrayof the seal shoes; and a plurality of spring elements, each of thespring elements radially between and connecting a respective one of theseal shoes with the seal base.
 14. The assembly of claim 13, wherein theminor region is configured as a portion of the first seal shoe at thefirst shoe end with a plurality of apertures therein.
 15. The assemblyof claim 14, wherein a first of the apertures extends partially axiallyinto the first seal shoe from the first shoe end and laterally withinthe first seal shoe.
 16. The assembly of claim 13, wherein the minorregion is configured with a lattice structure.
 17. The assembly of claim13, wherein the minor region is configured with a cellular structure.18. The assembly of claim 13, wherein the major region comprises a firstmaterial and the minor region comprises a second material different fromthe first material.
 19. A non-contact seal assembly, comprising: aplurality of seal shoes arranged about a centerline in an annular array,the seal shoes including a first seal shoe extending axially along thecenterline between a first shoe end and a second shoe end, wherein anaperture extends partially axially into the first seal shoe from thefirst shoe end and laterally through the first seal shoe along an entirelateral length of the first seal shoe; a seal base circumscribing theannular array of the seal shoes; and a plurality of spring elements,each of the spring elements radially between and connecting a respectiveone of the seal shoes with the seal base.
 20. An assembly for rotationalequipment with an axial centerline, the assembly comprising: a statorstructure; a rotor structure; and a seal assembly configured tosubstantially seal an annular gap between the stator structure and therotor structure, the seal assembly comprising a hydrostatic non-contactseal device including a plurality of seal shoes, a seal base and aplurality of spring elements; the seal shoes arranged about a centerlinein an annular array, the seal shoes sealingly engaging the rotorstructure and including a first seal shoe extending axially along thecenterline between a first shoe end and a second shoe end, wherein anaperture extends partially axially into the first seal shoe from thefirst shoe end and laterally within the first seal shoe, wherein theseal shoes circumscribe and sealingly engage the rotor structure; theseal base circumscribing the annular array of the seal shoes, the sealbase mounted with the stator structure; and each of the spring elementsradially between and connecting a respective one of the seal shoes withthe seal base.